The IEEE (Institute of Electrical and Electronics Engineers) 802.16e standard has been adopted back in 2007 as the sixth standard for IMT (International Mobile Telecommunication)-2000 by ITU-R (ITU-Radio communication sector) in the ITU (International Telecommunication Union).
IEEE 802.16 WG (Working Group) has determined late in 2006 to proceed with the IEEE 802.16m project to draft an amendment standard for the existing IEEE 802.16e as a standard for IMT-Advanced systems. As can be guessed from the target, the standard IEEE 802.16m includes two aspects; one past continuity as an amendment to IEEE 802.16e and one future continuity in terms of a standard for next generation IMT-Advanced systems. Accordingly, IEEE 802.16m is required to satisfy advanced requirements for IMP-Advanced systems while maintaining compatibility with mobile WiMax systems based on IEEE 802.16e.
Since IEEE 802.16m systems have backward compatibility, they may support terminals which support IEEE 802.16e systems as well as terminals which support IEEE 802.16m systems. When IEEE 802.16m systems support 802.16e terminals, it may be called legacy support mode.
There is a need of methods for more efficiently assigning radio resources in the legacy support mode.